In an image sensor used in single-CCD video cameras, red, green, and blue filters are provided on each photo detector (e.g., photodiode) to produce color images.
In three-CCD video cameras, incident light is separated into three light components, i.e., red, green, and blue with an optical prism and each of the light components is detected with three separate image sensors.
Hitherto, in order to check wavelength and intensity of incident light, a spectroscopic separation is performed using a grating or the like and the intensity distribution of each light component is then measured with a power meter or the like.
A trial for obtaining color information of red, green, and blue with a single photodiode is also known (refer to Patent Document 1 below). According to this approach, three diffusion layers having a depth of 0.2 μm, 0.6 μm, and 2 μm are disposed on a silicon substrate so as to overlap with each other, and currents generated from each junction are detected.
[Patent Document 1]
U.S. Pat. No. 5,965,875 (the fourth column to the fifth column, FIG. 6)